In the old days, you were able to curate your own feed, set that to be the default, and see posts in chronological order.
Now, there are tons of barriers against doing that. "For you" feeds, and even where you can set things up to see posts from only your friends/following list, you don't see things in chronological order, whether you want to or not.
Platforms shouldn't have the right to shove content in front of you and prevent you from curating your own social media. That's what makes it harmful for kids. Not the fact that it's "social media".